Threading, game loop, highlighted blocks

* src/Player.java: Added threading components. Added knowledge of color
* src/ComputerPlayer.java: Threaded. promptMove to start evaluating
board, isDone and getMove to retrieve results
* src/HumanPlayer.java: Threaded. promptMove to activate mouse listener,
isDone and getMove to retrieve results
* src/Game.java: Removed getHumanMove
* src/StandardChessGame.java: Added game loop, each tick 30 ms. Moved
selection mechanism to HumanPlayer.
* src/StandardChessGameAnimation.java: Adjusted animation for slightly
changed functions
* src/StandardChessGameGraphics.java: Added function to highlight
blocks.
* New files: Images/blockW, Images/blockB, Images/blockMovable